I ran it 25 times before getting a single bow; have heard of others running it even more. The bow drop rate was nerfed some time ago. Shame because of how critical it is for all stam damage dealers.
My first bow has dropped after ~140 clears. You're not even half way there . Some people got theirs after first clear. That's RNG. Everything's fine, just bad luck. Keep playing, it will drop eventually.
As far as I know, there is equal chance to get any kind of weapon. The problem is there are four kinds of 1h, three kinds of 2h, four kinds of staves, the useless s&b and only one bow.
My friend, mag sorc, started to farm vMA recently for Electro staff. So far he got 2-H axe, axe, dagger, sword and shield and a bow. So yes it does drop
I have completed vMA less then 100 times, most of those were last year when it was double drop, out of all those, I have got more then 10 bows, including 3 sharp